I want to change some cell color,but seem can't change my correct color..

example: i want change the cell to RED,I click the COLOR BOX to red, it changed the cell to BLUE.

or if I want change it to BLUE,it will change to BROWN...

my OS is XP with SP3, Ms Excel 2003, any one know? seem many excel file have this problem. but if I send this excel to other computer, it is normal...

why?